Internal combustion engine and a method for such an engine

Abstract

A method for controlling a diesel engine in a vehicle is presented. The engine comprises at least one cylinder, a fuel injector for each cylinder for injecting fuel into the respective cylinder, and a throttle valve for controlling the flow of air into the cylinder. The throttle valve is adjusted to assume a not fully open position if an amount of fuel injected into the at least one cylinder is equal to or less than a fuel injection threshold value.

Description

TECHNICAL FIELD[0001]The present invention relates to an internal combustion engine for a vehicle, and more particularly to a diesel engine comprising at least one cylinder, a fuel injector for each cylinder for injecting fuel into the respective cylinder, and a throttle valve for controlling the flow of air into the cylinder.BACKGROUND AND SUMMARY OF THE INVENTION[0002]In a normal operational situation of a vehicle engine, the difference between the exhaust gas temperature, and the ambient air temperature can reach 800° C. or more. The temperature difference can cause large thermal stresses in the exhaust manifold, in turn resulting in a risk of cracks appearing in the manifold. A known way to solve this problem is to use high strength materials for the manifold, which, apart from being expensive, often have the disadvantage of being difficult to process when manufacturing the manifold.[0003]Therefore, inventors herein have recognized it is important to make the manufacturing of ex...

AI Technical Summary

Benefits of technology

The invention is about controlling the temperature of an exhaust manifold in an internal combustion engine to reduce the risk of cracks and other failures. The method involves controlling the throttle valve to decrease the flow of cold air through the engine and into the exhaust manifold, which can cause thermal stresses. By controlling the throttle valve to a not fully open position, the amount of fuel injected into the engine is reduced, which in turn reduces the need for expensive high-temperature materials for the manifold. The method can be used with both diesel and gas engines and is based on various factors such as engine speed, fuel injection threshold value, and exhaust manifold temperature. The technical effect of the invention is to reduce the risk of failures in the exhaust manifold and to decrease the need for expensive materials while still maintaining sufficient engine performance.

Problems solved by technology

The temperature difference can cause large thermal stresses in the exhaust manifold, in turn resulting in a risk of cracks appearing in the manifold.

A known way to solve this problem is to use high strength materials for the manifold, which, apart from being expensive, often have the disadvantage of being difficult to process when manufacturing the manifold.

The inventors have discovered that diesel engines subjected to a lot of overrun (motor brake), i.e., fuel injection shut-down while the crankshaft is turning, compared to engines subjected to less overrun, present higher amount of material failures in the exhaust manifold.

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